1. Field of the Invention
Example embodiments of the present invention relate to a vertical positive-intrinsic-negative (pin) diode, and more particularly, to a vertical pin diode for plasma activation of a solid-state plasma antenna.
2. Description of Related Art
A solid-state plasma antenna refers to an antenna which transmits a signal using variability of a semiconductor substrate (change from a dielectric to a conductor). More specifically, an electrical or optical stimulus is applied to a desired region of a semiconductor substrate, which is normally in a dielectric state, for a desired period of time so that the semiconductor substrate is changed to be in a conductive state (i.e., in a plasma state), and a signal can be transmitted through the conductive region. Directions of beams and a frequency range of radio waves can be easily controlled by appropriately using such variability using a simple structure of the solid-state plasma antenna.
Horizontal pin diodes and vertical pin diodes are known as positive-intrinsic-negative (PIN) diodes included in solid-state plasma antennas. A horizontal pin diode has a structure in which a positive (P) region, an intrinsic (I) region, and a negative (N) region are arranged in a lateral direction on a substrate. An example of such a horizontal pin diode is disclosed in U.S. Pat. No. 6,617,670 entitled “Surface PIN Device.” Further, a vertical pin diode has a structure in which a positive (P) region, and intrinsic (I) region, and a negative (N) region are stacked in a vertical direction on a substrate, and an example of such a vertical pin diode is disclosed in each of U.S. Patent Application Publication No. 2012/0001305 A1 entitled “Method of Manufacturing Vertical PIN Diode” and U.S. Patent Application Publication No. 2015/0228807 A1 entitled “Vertical PIN Diode.” When compared to horizontal pin diodes of which charges are concentrated on a surface of an intrinsic region thereof and the concentration of charges is decreased in a downward direction from the surface, vertical pin diodes are advantageous in that charges thereof are uniformly dispersed in an intrinsic region thereof.
However, conventional vertical pin diodes are not only difficult to manufacture, but also can cause radio wave interference due to conductive components disposed inside the substrate, particularly intrinsic regions of the substrate. For example, the vertical pin diode disclosed in U.S. Patent Application Publication No. 2012/0001305 A1 entitled “Method of Manufacturing Vertical PIN Diode” is disadvantageous in that the vertical pin diode is difficult to manufacture due to a complicated manufacturing process because metal interconnections are disposed under trenches formed in the substrate. When such a vertical pin diode is applied to an antenna, radio wave interference can be caused by the metal interconnections. In addition, the vertical pin diode disclosed in U.S. Patent Application Publication No. 2015/0228807 A1 entitled “Vertical PIN Diode” is disadvantageous in that not only radio wave interference can be caused due to connection regions passing through intrinsic regions, but also a manufacturing process thereof is difficult.